Ras-related protein Rap-2b (RAP2B)
The protein contains 183 amino acids for an estimated molecular weight of 20504 Da.
Small GTP-binding protein which cycles between a GDP-bound inactive and a GTP-bound active form. Involved in EGFR and CHRM3 signaling pathways through stimulation of PLCE1. May play a role in cytoskeletal rearrangements and regulate cell spreading through activation of the effector TNIK. May regulate membrane vesiculation in red blood cells. (updated: April 1, 2015)
Protein identification was indicated in the following studies:
- Goodman and co-workers. (2013) The proteomics and interactomics of human erythrocytes. Exp Biol Med (Maywood) 238(5), 509-518.
- Lange and co-workers. (2014) Annotating N termini for the human proteome project: N termini and Nα-acetylation status differentiate stable cleaved protein species from degradation remnants in the human erythrocyte proteome. J Proteome Res. 13(4), 2028-2044.
- Hegedűs and co-workers. (2015) Inconsistencies in the red blood cell membrane proteome analysis: generation of a database for research and diagnostic applications. Database (Oxford) 1-8.
- Wilson and co-workers. (2016) Comparison of the Proteome of Adult and Cord Erythroid Cells, and Changes in the Proteome Following Reticulocyte Maturation. Mol Cell Proteomics. 15(6), 1938-1946.
- Bryk and co-workers. (2017) Quantitative Analysis of Human Red Blood Cell Proteome. J Proteome Res. 16(8), 2752-2761.
- D'Alessandro and co-workers. (2017) Red blood cell proteomics update: is there more to discover? Blood Transfus. 15(2), 182-187.
- Chu and co-workers. (2018) Quantitative mass spectrometry of human reticulocytes reveal proteome-wide modifications during maturation. Br J Haematol. 180(1), 118-133.
Methods
The following articles were analysed to gather the proteome content of erythrocytes.
The gene or protein list provided in the studies were processed using the ID mapping API of Uniprot in September 2018. The number of proteins identified and mapped without ambiguity in these studies is indicated below.
Only Swiss-Prot entries (reviewed) were considered for protein evidence assignation.
| Publication | Identification 1 | Uniprot mapping 2 | Not mapped / Obsolete | TrEMBL | Swiss-Prot |
|---|---|---|---|---|---|
| Goodman (2013) | 2289 (gene list) | 2278 | 53 | 20599 | 2269 |
| Lange (2014) | 1234 | 1234 | 7 | 28 | 1224 |
| Hegedus (2015) | 2638 | 2622 | 0 | 235 | 2387 |
| Wilson (2016) | 1658 | 1528 | 170 | 291 | 1068 |
| d'Alessandro (2017) | 1826 | 1817 | 2 | 0 | 1815 |
| Bryk (2017) | 2090 | 2060 | 10 | 108 | 1942 |
| Chu (2018) | 1853 | 1804 | 55 | 362 | 1387 |
1 as available in the article and/or in supplementary material
2 uniprot mapping returns all protein isoforms as one entry
The compilation of older studies can be retrieved from the Red Blood Cell Collection database.
The data and differentiation stages presented below come from the proteomic study and analysis performed by our partners of the GReX consortium, more details are available in their published work.
This protein is annotated as membranous in Gene Ontology.
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Biological Process
Negative regulation of cell migration
Neutrophil degranulation
Platelet activation
Platelet aggregation
Positive regulation of protein autophosphorylation
Rap protein signal transduction
Regulation of protein tyrosine kinase activity
Signal transduction
Cellular Component
Bicellular tight junction
Cell-cell contact zone
Cytosol
Extracellular exosome
Membrane
Membrane raft
Plasma membrane
Recycling endosome membrane
Specific granule membrane
Tertiary granule membrane
Molecular Function
G protein activity
GDP binding
GTP binding
GTPase activity
Protein domain specific binding
The reference OMIM entry for this protein is 179541
Ras-related protein 2b; rap2b
CLONING
Ohmstede et al. (1990) screened a platelet cDNA library with monoclonal antibody that recognizes a highly conserved epitope of Ras p21 (see 190020) involved in GTP binding. They identified a protein that is structurally and functionally similar to but distinct from RAP1A (179520), RAP1B (179530), and RAP2A (179540). RAP2B has a characteristic Ras-type C-terminal motif for polyisoprenylation, and 2 C-terminal cysteines suggesting that it may also be palmitoylated. Recombinant RAP2B had an apparent molecular mass of 22 kD. The deduced RAP2B protein contains 183 amino acids (Farrell et al., 1990). By RT-PCR, Greco et al. (2006) detected RAP2B in purified human reticulocytes. Western blot analysis of fractionated cells revealed the association of RAP2B with cell membranes.GENE FUNCTION
Ohmstede et al. (1990) demonstrated that recombinant RAP2B bound GTP. By cell fractionated and Western blot analysis, Torti et al. (1993) found that RAB2B was detergent soluble in resting platelets, but a significant amount of RAP2B was associated with the cytoskeleton in platelets aggregated with thrombin (176930), a thromboxane analog, or a Ca(2+)-ATPase inhibitor. Translocation of RAP2B to the cytoskeleton was strictly dependent on platelet aggregation. Inhibition of fibrinogen (see FGA, 134820) binding to the glycoprotein IIb (607759)-IIIa (173470) complex completely prevented the interaction of RAP2B with the cytoskeleton. Greco et al. (2006) found that membrane-associated RAP2B was activated upon treatment of normal human reticulocytes with calcium and a calcium ionophore. RAP2B was enriched in microvesicles released by calcium-activated reticulocytes, suggesting a role for RAP2B in membrane shedding.MAPPING
The International Radiation Hybrid Mapping Consortium mapped the RAP2B gene to chromosome 3 (TMAP SHGC-77468). ... More on the omim web site
Feb. 2, 2018: Protein entry updated
Automatic update: Uniprot description updated
Dec. 19, 2017: Protein entry updated
Automatic update: Uniprot description updated
June 20, 2017: Protein entry updated
Automatic update: comparative model was added.
March 16, 2016: Protein entry updated
Automatic update: OMIM entry 179541 was added.